Many attempts have been made in the past for testing the characteristics of a bottle such as the degree of stretch on plastic bottles that takes place when they are pressurized. One such device is disclosed in U.S. Pat. No. 4,090,394 wherein pressurized fluid is forced into a plastic bottle by means of a piston and by sensing the movement of the piston the amount of stretch in the bottle can be determined.
In U.S. Pat. No. 3,894,424, hydrostatic pressure is utilized for testing the strength of bottles and the like. One problem with both of these devices is that they are relatively fixed structures.
Other volumetric testing devices for bottles and leak detectors are disclosed in U.S. Pat. Nos. 3,060,735, 3,683,677, 3,751,973, 3,951,185, 3,762,213, 3,805,593, 3,943,819 and 3,954,004.